A Complementary Metal-oxide Semiconductor (CMOS) image sensor is capable of transforming the function of pure logic operation into receiving external light rays, converting them into electric energy and transmitting it out.
For an active pixel sensor (APS) circuit, as the most common detection circuit of a CMOS image sensor, during the process of photoelectric conversion performed by a photosensitive device, the difference in the process of source follower thin film transistors (TFT) themselves causes the threshold voltages thereof to be non-uniform, and the output current of the source follower TFTs would be affected by the threshold voltage thereof, thus the output current of the source follower TFTs is non-uniform, resulting in distortion in the final image.